1. Field of the Invention
The present invention relates to two-way cable television communications systems and, more particularly, to a method of and apparatus for establishing emergency communications between a master station and one or more remote stations in such a system.
2. Technical Consideration in Prior Art
In most two-way cable television communications systems, for example, the system set forth in Osborn et al Pat. No. 3,794,922 and Osborn U.S. Pat. No. 3,803,491, video information, in the form of imported or locally originated television programs may be transmitted from a central station to a plurality of remote stations when a viewer at the remote location switches on a television receiver at the remote station, which is coupled to the master station through a coaxial cable network. During emergencies, for example, civil defense emergencies, it would be desirable to provide such systems with the capability of transmitting both video and audio information to the remote stations, regardless of whether or not the television receivers at the remote locations are on or off in order to insure that emergency civil defense instructions or other emergency information such as local flood or tornado warnings can be communicated to subscribers or viewers at the remote stations. It is further desirable to alert the viewer that an emergency transmission is forthcoming and to provide a preassigned emergency alert channel which can be automatically tuned from the master station.